1. Field of the Present Invention
The present invention generally relates to the field of computers and more particularly to a circuit board design for enhanced cooling in a computer system.
2. History of Related Art
Computer systems including personal computers, servers systems, and enterprise systems are universally prevalent in a vast assortment of business, scientific, commercial, and home applications. The thermal generation characteristics of the semiconductor technology that drives essentially all computer systems have been well documented and heat dissipation in computer systems has been a design and manufacturing concern from the inception of the industry.
Several emerging trends in computer design have heightened the need for efficiently dissipating heat in computer systems. Among these trends, the desire to increase the number of features packaged within a given system by increasing the number of expansion or I/O cards connected to the system, the desire to decrease the size of the computer system chassis or box, and the ever increasing power dissipated by the emerging generation of I/O cards due to increased functionality and performance, have all resulted in unprecedented levels of thermal generation.
Accommodating more I/O cards without increasing the chassis dimensions results in decreased spacing between adjacent I/O cards. The reduced spacing translates directly into reduced air flow between adjacent cards and hence higher component temperatures. Typically, I/O cards are inserted into an expansion board or planar that either connects to or is an integral part of the computer system's processor board or motherboard. The expansion board includes multiple connectors for attaching I/O cards. Frequently, the problems of adequately dissipating the heat generated by the I/O cards is in part a result of the poor air flow that is characteristic of certain regions of the I/O cards. Typically, the region of the I/O card proximal to the corner formed by the rear face of the chassis and the planar has poor air flow. As the connector pitch in these planars decreases and/or the functionality and performance of the I/O cards increases, the heating problem of providing adequate air circulation to remote portions of I/O cards increases.
Inadequate heat dissipation on computer systems detrimentally affects system performance and reliability. As the temperature of the semiconductor components of the system increase, the speed at which the devices operate decreases. If the temperature increases beyond a specified threshold, the devices may experience temporary or permanent thermal breakdown. Typically, air moving devices (AMD's) such as fans or blowers are introduced into the computer system to increase air flow and to maximize heat dissipation. As board-to-board spacing or pitch continues to decrease, however, the benefit achieved by adding more AMD's or higher speed AMD's into the computer system is reduced. Additionally, it is desirable to minimize the use of AMD's in a computer system because each AMD consumes valuable space that could otherwise be dedicated to system electronics, increases system cost, and undesirably increases the system noise level. Accordingly, it is highly desirable to provide for an enhanced cooling method that addresses the greater challenges presented by densely spaced higher performance I/O cards required in present day systems without significantly increasing system cost and without significantly decreasing system performance or reliability.